This invention generally relates to thermodynamic modeling for enclosures. More particularly, embodiments of this invention relate to modeling of internal environmental behavior of an enclosure for use by an HVAC control system.
In conditioning a building such as dwelling other enclosure one or more system for heating, ventilating and air conditioning (HVAC) are typically used. HVAC control systems need to make decisions as to how to condition the enclosure appropriately. Since the enclosure has an associated thermal mass that needs to be heated or cooled, how and when the heating or cooling is carried out can greatly impact the energy efficiency as well as the cost of the process.
Conventionally, a structural model, that attempts to specify how the enclosure will behave under the influence of an HVAC system, is created based on various factors (size, windows, orientation, etc.). That model is then used to specify the type and size of HVAC system to install and/or it is used by the HVAC control system throughout the lifetime of the building. For example, U.S. Pat. No. 7,072,727 discusses a method for determining heat loss of a building and for the proper sizing of HVAC equipment for the building.
It is also known for model updates to occur after installation through simple calculations such as adding heat and measuring time and temperature. For example, U.S. Pat. No. 5,555,927 discusses an adapted recovery method for a setback thermostat using the intersection of the space temperature with a sloped recovery temperature line which approximates the change in temperature as a function of time during recovery of the temperature controlled space from the setback temperature, to determine the time at which recovery to the occupancy temperature should begin. The recovery line slope is re-calculated and updated.
U.S. Patent Application Publication No. 2005/0192915 discusses a system for forecasting predicted thermal loads for a building including a neural-network-based thermal load predictor. The neural network can be trained using building data, occupancy data and actual weather conditions. A thermal condition forecaster uses a simple regression model based on forecasted high and low temperatures for a specific locale and measured local temperature and humidity observations made immediately prior to the prediction.
Systems and methods for modeling the behavior of an enclosure for use by a control system of an HVAC system installed in the enclosure are described herein. According to some embodiments method, weather forecast data predicting future weather conditions for a region including the location of the enclosure are received. A model for the enclosure that describes the behavior of the enclosure for use by the control system is updated based on the weather forecast data. The HVAC system for the enclosure is then controlled using the updated model for the enclosure.
According to some embodiments, the weather forecast data includes predictions more than 24 hours in the future, and can include predictions such as temperature, humidity and/or dew point, solar output, precipitation, wind and natural disasters. According to some embodiments the model for the enclosure is updated based also on historical weather data such as temperature, humidity, wind, solar output and precipitation.
According to some embodiments, the model for the enclosure is updated based in part on the occupancy data, such as predicted and/or detected occupancy data. The model for the enclosure updating can also be based calendar data.
According to some embodiments, the model for the enclosure is updated based also on the data from the one or more weather condition sensors that sense current parameters such as temperature, humidity, wind, precipitation, and/or solar output. According to some embodiments, the locations of the weather condition sensors can be automatically detected.
According to some embodiments, the model for the enclosure is updated based also on an enclosure model stored in a database, and/or on enclosure information from a user.
According to some embodiments systems and methods are described for modeling internal environmental behavior of an enclosure that includes actively inducing a change in the internal environment of the enclosure, measuring a response of the internal environment of the enclosure from the induced change, and updating a model for the enclosure that describes behavior of the enclosure for use by the control system based at least in part on the measurement of the response from the induced change.
According to some embodiments the change is actively induced primarily for purposes of updating the model for the enclosure, rather than for conditioning the internal environment of the enclosure. The change can be actively induced in response to input by a user, or it can be induced automatically by the processing system for example due to the type of enclosure or a change in season. The change is preferably induced at a time when the enclosure is likely to be unoccupied. The induced change, for example, can be heating and/or cooling by the HVAC system.
As used herein the term “model” refers generally to a description or representation of a system. The description or representation can use mathematical language, such as in the case of mathematical models. Examples of types of models and/or characteristics of models, without limitation, include: lookup tables, linear, non-linear, deterministic, probabilistic, static, dynamic, and models having lumped parameters and/or distributed parameters.
As used herein the terms “profile,” “structure profile,” “structure model,” “enclosure profile,” “enclosure model,” “building profile,” “building model” and the like refer to any numerical or mathematical description or models of at least some of thermodynamic behavioral characteristics of a building, enclosure and/or structure, for example for use in HVAC applications.
As used herein the term “sensor” refers generally to a device or system that measures and/or registers a substance, physical phenomenon and/or physical quantity. The sensor may convert a measurement into a signal, which can be interpreted by an observer, instrument and/or system. A sensor can be implemented as a special purpose device and/or can be implemented as software running on a general-purpose computer system.
As used herein the term “structure” includes enclosures and both non-buildings and buildings. As used herein the term “enclosure” means any structure having one or more enclosed areas, and also includes any building. Examples of structures and enclosures include, but are not limited to: residential buildings, commercial buildings and complexes, industrial buildings, sites and installations, and civil constructions.
As used herein the term “thermodynamic” includes all state variables that can be used to characterize a physical system. Examples of thermodynamic variables include, but are not limited to: pressure, temperature, airflow, humidity, and particulate matter.
It will be appreciated that these systems and methods are novel, as are applications thereof and many of the components, systems, and methods employed therein. It should be appreciated that embodiments of the presently described inventive body of work can be implemented in numerous ways, including as processes, apparatuses, systems, devices, methods, computer readable media, and/or as a combination thereof. Several illustrative embodiments are described below.